php renato

gistfile1.txt

<?php

$HEIGHT = 600;
$WIDTH = 1000;

$xfactor = 2; 5;
$yfactor = 1; 0.001; 0.5;

$CENTER_X = $WIDTH/2;
$CENTER_Y = 400;

$img = imagecreate($WIDTH, $HEIGHT);
imagecolorallocate($img, 255, 255, 255);
$COLOR = imagecolorallocate($img, 22, 22, 22);

function tY ($y) {
	global $CENTER_Y;
	return $CENTER_Y-$y;
}

function tX ($x) {
	global $CENTER_X;
	return $CENTER_X+$x;
}

function fY ($y) { // transforms vertical
	global $yfactor;
	return tY($y*$yfactor);
}

function fX ($x) {
	global $xfactor;
	return tX($x*$xfactor);
}

function drawPoint ($x, $y, $thick=4) {
	global $img;
	imagefilledellipse($img, fX($x), fY($y), $thick, $thick, 1);
}

//

function makeDot ($x, $y) {
	global $img;
	imageline($img, fX($x), fY($y), fX($x), fY($y), 1);
}

function drawLine ($x1, $y1, $x2, $y2) {
	global $img, $COLOR;
	imageline($img, fX($x1), fY($y1), fX($x2), fY($y2), $COLOR);
}

function drawDashedLine_f ($x, $x1, $y1, $x2, $y2, $dsize) {
	return (($y2-$y1)/($x2-$x1)*$x)+$x1;
}

function drawDashedLine ($x1, $y1, $x2, $y2, $dsize=2) {	

	if ($y2 < $y1)
		list($y1,$y2) = array($y2,$y1);
	if ($x2 < $x1)
		list($x1,$x2) = array($x2,$x1);

	if ($x1==$x2) {
		for ($i=0; $i<($y2-$y1)/$dsize; $i+=2) {
			drawLine($x1, $y1+$i*$dsize, $x1, $y1+($i+1)*$dsize);
		}
		return;
	}

	if ($y1==$y2) {
		global $xfactor;
		for ($i=0; $i<($x2-$x1)/$dsize; $i+=2) {
		//	echo $i, " ", $x2-$x1;
			drawLine($x1+$i*$dsize, $y1, $x1+($i+1)*$dsize, $y1);
		}
		return;
	}

	return;
	for ($i=0; $i<($y2-$y1)/$dsize; $i+=2) {
		// echo "<br>$i";
		$x = $i*$dsize;
		$y = drawDashedLine_f($x, $x1, $y1, $x2, $y2, $dsize);
		$xfinal = ($i+1)*$dsize;
		$yfinal	= drawDashedLine_f($xfinal, $x1, $y1, $x2, $y2, $dsize);
		
		// echo "$x, $y: $xfinal, $yfinal<p>";
		drawLine($x+$x1, $y, $xfinal+$x1, $yfinal);
	}
	
}

function drawGrid ($dsize=20) {
	global $img,
		$CENTER_X, $CENTER_Y,
		$WIDTH, $HEIGHT, $COLOR,
		$xfactor, $yfactor;
	// $dsize /= $xfactor;

	$COLOR = imagecolorallocate($img, 200, 200, 200);

	// vertical
	for ($i=0; $i<$WIDTH/$dsize; $i++) {
		drawLine($i*$dsize,
			$CENTER_Y/$yfactor,
			$i*$dsize,
			(-$HEIGHT+$CENTER_Y)/$yfactor);
	}
	for ($i=0; $i<$WIDTH/$dsize; $i++) {
		drawLine(-$i*$dsize,
			$CENTER_Y/$yfactor,
			-$i*$dsize,
			(-$HEIGHT+$CENTER_Y)/$yfactor);
	}
	
	// horizontal
	for ($i=0; $i<$HEIGHT/$dsize/$yfactor; $i++) {
		drawLine(-$CENTER_X*$xfactor,
			-$i*$dsize,
			($WIDTH-$CENTER_X)*$xfactor,
			-$i*$dsize);
	}
	for ($i=0; $i<$HEIGHT/$dsize/$yfactor; $i++) {
		drawLine(-$CENTER_X*$xfactor,
			$i*$dsize,
			($WIDTH-$CENTER_X)*$xfactor,
			$i*$dsize);
	}
	
	$COLOR = imagecolorallocate($img, 22, 22, 22);
}

function drawAxes () {
	global $CENTER_X, $CENTER_Y, $WIDTH, $HEIGHT, $img, $xfactor, $yfactor;
	$COLOR = imagecolorallocate($img, 200, 200, 200);
	drawLine(-$CENTER_X/$xfactor, 0, ($WIDTH-$CENTER_X)/$xfactor, 0); // horizontal
	drawLine(0, $CENTER_Y/$yfactor, 0, (-$HEIGHT+$CENTER_Y)/$yfactor); // vertical
	$COLOR = imagecolorallocate($img, 22, 22, 22);
}


$A = .1;
$B = 23;
$C = 0;

function workEquation () {
   
	global $CENTER_X, $WIDTH;
	// $A, $B, $C;

	function workEquation_f($x) {
		global $A, $B, $C;
		return $A*pow($x, 2)+$B*$x+$C;
	}
   
	function workEquation_fy($y) {
		global $A, $B, $C;
		return (-$B+sqrt(pow($B,2)-4*$A*$C))/2/$A;
	}

	function workEquation_ffy($y) {
		global $A, $B, $C;
		return (-$B-sqrt(pow($B,2)-4*$A*$C))/2/$A;
	}

	function maxY () {
		global $A, $B, $C;
		return -(pow($B, 2)-4*$A*$C)/4/$A;
	}

	function maxX () {
		global $A, $B, $C;
		return -$B/2/$A;
	}

	drawPoint(workEquation_fy($y), 0, 7);
	drawPoint(workEquation_ffy($y), 0, 7);
   
	global $xfactor, $yfactor;

	$istart = -$CENTER_X/$xfactor;
	$iend = ($WIDTH-$CENTER_X)/$xfactor;
   
	$x = $istart;
	$y = workEquation_f($x);

	drawPoint(maxX(), 0);
	drawPoint(maxX(), maxY());
	drawDashedLine(maxX(), 0, maxX(), maxY());
	drawDashedLine(0, maxY(), maxX(), maxY());

	for ($i=$istart; $i<$iend; $i++) {
		$lx = $x;
		$ly = $y;
		$x = $i;
		$y = workEquation_f($x);
		drawLine($lx, $ly, $x, $y);
	}
}


drawGrid();
drawAxes();
workEquation();

// drawDashedLine(10, 10, 10, 200);

header('Content-Type: image/png');
imagepng($img);

?>